Some things pass for music and art these days that have no business in that category. And I think we can all think of examples. Much of the music and art of today is warped and degenerate - it is the ugly fruit of humanistic atheism. Can anyone think of anything beautiful that came out of the USSR? I can't. Atheism is just plain Ugly with a capital U.
Much of the music of Shostakovich and Prokofiev is very beautiful. You are almost certainly familiar with Prokofiev's 'Troika' from the Lieutenant Kije Suite; it's been co-opted, usually without attribution, as a standard piece of Christmas music; yet it was written as the soundtrack for a Bolshevik propaganda film.
Bulgakov's The Master and Margarita, and other dissident art also qualifies as great.
As for atheists, Ayn Rand was a atheist, and a great writer and philosopher.
Well, in the early days there were the films of Eisenstein and Dovzhenko, but once Stalin came along there wasn't much.
Eisenstein's movies, Vinogradov's math, Illych-Schvitich's linguistics